In rotating machines, such as turbines, power expanders, power plant fans, pumps, and the like, a fluid, such as a liquid or gas is often rotated through the machine. Frequently, the liquid or gas component contains suspended solids. When these solids strike against the exposed surfaces of the machine, it can cause accelerated wear on the machine surfaces. This wear generally does not occur evenly, and greater wear is seen in areas where the solids are projected against the surface, or currents or eddies form in the gas or liquid stream, retaining a portion of the stream in contact with part surfaces for an extended time. Often, the solid material will completely wear away the machine parts, necessitating repair or replacement of the worn parts. Often, these assemblies are located deep inside machinery, and the entire system must be shut down and dismantled to gain access to worn parts. A longer time duration between machine shutdowns, which increases productivity and reduces down time, is desirable in these circumstances.
One solution to this wear problem has been to place a coating or liner on the exposed surfaces which are subject to wear to slow or reduce the wear. When the liners on the areas more subject to wear have deteriorated, they can be replaced, eliminating the need to replace the entire part. However, thin coatings which are sprayed or painted on are often insufficient to slow wear significantly enough to warrant the expense and time of coating. Another solution has been to construct the rotating equipment of a material that is more resistant to wear. However, this tends to be cost-prohibitive because such materials are generally expensive, and are only needed in areas where there is actual contact of the solids with the surface. Yet another solution has been to attach a solid layer of wear-resistant material to the areas of the machinery that experience wear, or etching. However, difficulties have occurred with finding a means to adhere the wear-resistant material to the wear areas of the rotating equipment that will provide sufficient adhesion during operation of the equipment, but that can be removed when it becomes necessary to replace the wear-resistant material. Additionally, when a solid layer has been attached, difficulties have occurred with the solid material experiencing cracking or fracture failures when the machine starts or stops because the solid material is not flexible enough to withstand the torque applied during starting and stopping.
Therefore, what is needed is a means to slow or reduce wear in the areas of rotating equipment which see the greatest wear that is of sufficient durability that the equipment can go for long periods between replacement of the wear-resisting means, while finding a material that will not experience fractures during machine starts and stops.
Labyrinth seals are formed by layering, or lapping materials in a way to deflect or slow the flow of materials, or minimize leakage of materials through the seal. Labyrinth seals are frequently employed when it is desired to keep materials in, or out of, certain areas of equipment, such as keeping gases out of areas where sparks are generated, or keeping solids away from rotating drive shafts where the solids could accumulate, and slow or stop rotation, or damage the shafts by wear.
The present invention involves attaching a labyrinth seal to high wear areas in rotating machines to slow or reduce wear. The irregularly shaped adjacent edges where the material is lapped help to alter the normal turbulence paths across the surface of the rotating equipment, and thus reduce wear. Additionally, in areas that involve junctions of two parts, where the greatest amount of wear is generally seen, an additional layer of labyrinth seal can be attached to the joint areas to slow or reduce wear in these areas even further. Because the labyrinth seal is comprised of individual tiles, the seal has sufficient flexibility to move slightly and therefore withstand cracking or fracturing when the fan is started and stopped.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.